Kiln car



March 29, 1932. p MEEHAN 1,851,717

KILN CAR Filed Aug. 14, 1930 J7 J3 J J 1 I INVENTOR. F 341A 7, MEEH/IN 5' BY w 11 D Patented Mar. 29, 1932 UNITED s'rArEs PATENT- OFFICE PAUL A. MEEHAN, OI DAYTON, OHIO, ASSIGNOR TO SWINDELL-DRESSLER CORPORA- TION, OI PITTSBURGH, PENNSYLVANIA, A CORPORATION OF PENNSYLVANIA KILN OAR Original application filed August 28, 1928, Serial No. 301,508. Divided and this application fled Augult 14, 1930. Serial No. 475,161.

My present invention relates in general to the construction of cars or trucks used for supporting and movin metallic articles during an annealing or other heat treating process in a continuous kiln or furnace.

In annealing and analogous heat treating processes wherein metallic articles are progressively moved throu h a continuous tunnel kiln, it is an established practice .to enclose the articles in a container supported on one or more of the cars. When the cars with the container in position are passed into the kiln and subjected to the gradually increasing temperatures therein, any gases within the container expand and tend to escape therefrom. When metallic articles containing carbon have been heated to ap-.

proximately a red heat, the carbon reacts with any iron oxide present in the container to form an atmosphere within the box of almost pure carbon monoxide. No oxidation of the articles can occur as long as this reducing atmosphere is maintained in the container. After passing through the high temperature section of the kiln, the ases and articles in the container are gradua ly cooled and contract. The resultant lowering of the gas pressure therein permits the kiln chamber atmosphere or, if the car is then outside of the kiln, air, to be quickly drawn into the container. When this change in the container atmosphere occurs, the articles are rapidly oxidized.

This is especially harmful in the annealing of steel sheets subsequently used in forming automobile bodies as a surface finish of the highest degree is required for such use and cannot be attained if surface oxidization is allowed to take place during the annealing operation. In annealing such sheets, the sheets are arranged horizontally in one or more piles in each container. The upper sheets being less closely pressed together than the lower sheets of the pile will be subjected to substantial oxidization, while the lower sheets will develop blue or grey edges, which are also undesirable.

Oxidation of the sheets during or immediately after the annealing process can be prevented by maintaining the articles in a reducing atmosphere until they are cooled to substantially their final temperature and preferably, by continuously introducing reducing gases into the container during the annealing process and particularly during the cooling period thereof. In carrying out annealing operations of this character in a continuous tunnel kiln, it has been found extremely diflicult to maintain the necessary supply of reducing gases to the containers on the moving cars while preventing the entrance of other gases therewith and waste of the gases supplied.

The object of my present invention is the provision of a kiln car construction capable of transporting heavy loads under the extreme thermal conditions required in the annealing of steel sheets and incorporating improved provisions for receiving a suitable gas from a source of supply and distributing it to all parts of a container mounted thereon and enclosing the sheets being heat treated.

The various features of novelty which characterize my invention are pointed out with particularity in the claims annexed to and forming a part of this specification. For a better understanding of the invention, however, and the advantages possessed by it reference should be had to the accompanying drawings and descriptive matter in which I have illustrated and described a preferred embodiment of the invention.

Of the drawings:

Fig. 1 is a sectional elevation of a tunnel kiln oar embodying my invention;

gig. 2 is a section on the line 22 of Fig. 1; an

Fig. 3 is an enlarged sectional view of a portion of the car shown in Figs. 1 and 2.

In the drawings I have illustrated a preferred embodiment of my invention in which a tunnel kiln A having the usual refractory side walls A and crownA is provided with a chamber or goods passageway B extending longitudinally of the kiln. The lower portion of the kiln chamber is provided with track rails B at its bottom for kiln cars or trucks C. The kiln shown is of the muflie type, being heated by combustion chambers B resting on benches B at the side of the oods passageway. Eers B through which products of combustion pass lengthwise of the kiln have their heating walls formed with the customary circulating channels B, through WhlCl'l a convection current circulation of the kiln atmosphere is set up. In operation cars are in serted one at a time at the entrance end of the kiln and the train of cars normally filling the kiln is periodically advanced a car length by a car pusher (not shown) WhlCh may be of any suitable or usual type employed for the purpose. A new car 1s 1nserted at the entrance end of the kiln after each pushing operation.

Each of the goods carrying cars is preferably formed in three units, each of which comprises a body consisting of several massive blocks C of refractory material supported on a metallic framework C, on the lower side of which a plurality of pairs of track engaging wheels C are suitably mounted. cover plate D extending over and protecting the upper sides of the refractory blocks C The cover plate is preferably divided into two sections D and D arranged in overla ping relation and each formed. with a rib D projecting from its upper side and extending longitudinally of the car adjacent the outside edge of the section. A trough shaped groove or channel D with inclined sides and closed ends is formed in the upper side of each rib D A plurality of roller elements, such as cast iron or steel balls E, are mounted in each of the channels and form a support for a metal work support or tray G, which extends over the top of the assembled car units. The tray is formed at its underside with a pair of downwardly projecting longitudinally extending ribs G, each of which has a channel Gr in which the tops of the balls E in the car units below are received. A marginal flange G is formed on the tray. Kiln cars constructed as heretofore described are disclosed in my prior Patent No. 1,641,185, granted September 6, 1927.

The metal sheets to be annealed are arranged horizontally in piles on the tray and covered by a removable metallic cover H, which, as shown, is formed of heavy metal plates and stiffening members riveted together. The-cover is in the form of a box with a closed top and open bottom. Hooks H are provided on the sides of the box H to permit engagement by a suitable hoisting mechanism (not shown) for lowering the box on to and lifting it off the tray. The to of each box H is provided at points ad jacent its ends with one or more openings H adapted to be closed by removable plugs H. A sand seal H surrounds each plug and prevents the escape of gases from the interior of the box when the plugs are in posi- The combustion cliam-.

Each of the car units has a cast metal tion. The plugs can be removed to permit any air within the box to be swept out before the box is passed into the kiln and also to permit the escape of reducing gases after the car is moved out of the kiln chamber. A fire clay seal'H is also provided for sealing the line of contact between the lower edges of the box and the tray. 1

In carrying out my invention, one of the tray supporting balls in the central car unit. is especially formed as hereinafter described to provide a conduit connection between the interior of the box and the portion of the kiln chamber below the car body. This ball element is designated as K and has its lower portion K shaped to contact with the inclined sides of the groove D and shoulders K resting on the upper surfaces of the cover plate rib as shown particularly in Fig. 3, and welded to the rib in that position. The ball K is formed with a vertical passage K therethrough and registering at its lower end with a vertical passage D, extending through the subjacent rib D and refractory block C. A pipe D extends upwardly through the passages D and K to the center portion of the ball K. A fluid nozzle K is mounted in the upper end of the passage K and formed with an axial passage K, connected to the pipe I). The nozzle projects upwardly into an enlarged vertical passa e Gr formed in the tray G and rib G". A s allow groove G, into which the passage G opens, extends longitudinally in the tray bottom beneath the pile of sheets and provides a distribution of any gases from the pipe D to a series of transverse grooves G in the tray bottom. With this construction, any gas passing upwardly through the pipe D' will be distributed throughout the space enclosed by the box H and tray G. A gas-tight connection between the ball K and rib G is maintained by a shallow pan K surrounding and supported on the upper portion of the ball and lower end of the tray rib. The space betweenthe pan K and rib G 1s packed with fir'eclay, as shown in Fig. 3.

Various means may be provided for suping a reducing gas such as natural gas, 'e oven gas or producer gas to the boxes on the cars. In the construction illustrated, a supply pipe J is sup o-rted centrally beneaththe metallic car ame C and extends longitudinally thereof. This pipe is connected to the vertical pipe D by a lateral branch pipe J in which a control valve J 2 is mounted. The pipe J is provided adjacent its ends with cut-off valves J a and J A contral valve J carrying a hose connection J is incorporated in the pipe J. The pipe J is also provided with a hose connection J 7 at one end by which it is connected to the supply pipe J of the following car.

pl co As disclosed in. my prior applicati nv Serial No. 301,503, filed August 23, 1928, and

since matured into Patent No. 1,808,000,

granted June 2, 1931, of which the present application is a division, the supply pipe J of each car may be connected to a source of reducing gas located in a pit adjacent the entrance end of the kiln in the manner described therein or to a suitable source movable With or carried by the cars. In either case, the supply of gas to the pipe D can be suitably regulated by the control valve J to maintain a reducing atmosphere within the box during the portions of the annealing process requiring such conditions.

The car construction described is characterized by its mechanical strength, durability and avoidance of distortion of the exposed parts from thermal expansion and contraction. The location of the special supporting element K in the central car unit is not only beneficial from the point of gas distribution but also avoids any decrease in the thermal expansion and contraction properties of the construction. The construction and arrangement of the gas supply parts in the car is highly. advantageous, permitting the maintenance of the supply of gas without waste thereof and avoiding any necessity of disassembling parts thereof to permit the removal of the tray G when desired.

While in accordance with the. rovisions of the statutes, I have illustrate and described the best form of embodiment of my invention now known to me, it will be apparent to those skilled in the art that changes may be made in the form of the apparatus disclosed without departing from the spirit of my invention as set forth in the appended claims and that in some cases certain features of my invention may be used to advantage without a corresponding use of other features.

Having now described my invention what I claim as new and desire to secure by Letters Patent, is:

1. A tunnel kiln car comprising a body, a pluralit of supporting elements positioned on said ody, a work supporting and enclosing container mounted on said supporting elements, and means for conveying a fluid through said body and one of said supporting elements to the interior of said container.

2. A tunnel kiln car having a metallic frame, a refractory body supported on said frame, a metallic cover mounted on said refractory body and having a roove in its upper side, a plurality of rol er elements arranged in said groove, a work supporting and enclosing container mounted on said roller elements, and means for passing a fluid through said body and cover to the interior of said container.

3. A tunnel kiln car having a metallic frame, a refractory body supported on said frame, a metallic cover mounted on said refractory body having a groove in its upper side, a plurality of supporting elements 'arranged in said groove, a work supporting and enclosing container mounted for thermal expansion and contraction on said supporting elements, and means for conveying a fluid through said body, cover and one of said supporting elements to the interior of said contamer.

4. A tunnel kiln car comprising a plurality of car units, each having a metallic frame, a refractory body supported on said frame, a metallic cover mounted on said refractory body having a groove in its upper side, a plurality of roller elements arranged in said groove, a work supporting and enclosing container mounted on the roller elements of said car units, and means for passing a fluid through the body and cover of one of said car units to the interior of said container.

5. A tunnel kiln car having a refractory body, a conduit formed in said body, a metallic cover mounted on said refractory body, a plurality of longitudinal ribs on said cover having a groove in their upper sides, a plurality of supporting elements arranged in said grooves, one of said supporting elements being immovable in said groove, a goods carrying tray mounted on said supporting elements, a box supported on said tray and enclosing the goods carried thereby, a conduit connecting the interior of said box to said body conduit and a gas supply pipe arranged in said body conduit.

6. A tunnel kiln car having a refractory body, a vertical conduit in said body, a metallic cover mounted on said refractory body, a plurality of longitudinal ribs on said cover havlng a groove 1n their upper sides, a plurality of roller elements arranged in said grooves, one of said roller elements being fixed in said groove, a goods carrying metallic tray mounted on said roller elements, a

box supported on said tray and enclosing the goods carried thereby, a conduit in said fixed supporting element connecting the interior of said box to said body conduit, and sealing means for said element conduit.

7. A tunnel kiln car having a refractory body, a vertical conduit in said body, a metallic cover mounted on said refractory body, a plurality of longitudinal ribs on said cover having a groove in their upper sides, a plurality of supporting elements in said grooves, one of said elements being fixed in its groove, a goods carrying metallic tray mounted on and having grooved ribs receiving said supporting elements, a box supported on said tray and enclosing the goods carried thereby, conduits formed in one of said tray ribs and in said fixed supporting element and connecting the interior of said box to said refractory body conduit, and grooves extendingtransversely and longitudinally in said tray goods supporting surface.

4 ean-n7 Signed-at lDayton,'rin'th ty of Montgomeryfand fState rof @hio, this 9th 'day' 10f AugusQAxD. 1930.

. PAUL A. EME'EIIAN;,- 

